You are making a pretty strong case that as a theme, greed is more complex than one might think. I do not see pride as a source of greed, but a possible symptom of greed.

Loving something overmuch is intemperance, more akin to greed (and idolatry) than pride. In the example you provide, loving something you created can be called pride -- as in "look what I did!" -- but loving it overmuch takes it into the realm of greed. A greedy love , a jealous love, a destructive sense of ownership or entitlement. Pride may be an outward manifestation of these things but it is a mere wart on the ugliness of greed.

I'll grant you, Thorin's pride may have had something to do with wanting to regain his throne and former glory but to what end? To satisfy his greed...